Communication of conversation between terminasl over a radio link

ABSTRACT

A package device has one integrated circuit in a cavity in a package substrate and electrically coupled to one side of the package substrate. A second integrated circuit is mounted on another side of the package device and electrically coupled to that side as well. A third integrated circuit or more may be mounted on the second integrated circuit. Pads useful for testing are present on both sides of the package substrate. The integrated circuits may be tested before final encapsulation to reduce the risk of providing completed packages with non-functional integrated circuits therein.

FIELD OF THE INVENTION

This invention relates to communicating conversational data signalsbetween terminals over a radio link.

BACKGROUND OF THE INVENTION

More particularly, the invention relates to communicating conversationaldata signals between terminals over a radio link capable of full-duplextransmission of conversational data packets. One example of this type ofradio link is represented by the Bluetooth standards of the EuropeanTelecommunications Standards Institute (‘ETSI’). Bluetooth is atechnology that uses radio frequency (RF) transceivers to providepoint-to-multipoint wireless connectivity within a personal space.Bluetooth was designed for both voice and data communication at lowper-unit costs while consuming little power to achieve the cost andpower goals, Bluetooth limits connectivity to a sphere of about 10meters (more power hunger versions can stretch the effective range up to100 meters) while providing a maximum data rate of 723 kbps. Thecommunications may be used in wireless Personal Area Networks (‘PAN’s),to connect devices such as a portable telephone, an ear-phone/microphonehead-set, a personal digital assistant, a computer, a printer and so on,for example.

Certain of these applications involve conversational communication, thatis to say where data can be sent discontinuously from either one of twoterminals to the other and may be unidirectional at a given moment orbidirectional. A typical example of conversational communication towhich the present invention is applicable, without being limitedthereto, is audio communication, in particular vocal conversation.

The present invention is particularly applicable to communication ofconversational data signals of the above type in which theconversational data packets are transmitted in alternate directionswithin a pair of time slots, the communication comprising relativelyshort time periods each comprising a set of said time slots, as inBluetooth transmissions. Patent specifications WO0241606 and WO0205593describe communication systems of this general kind.

Cellular telephone systems, such as the Global Systems for Mobilecommunication (‘GSM’) system, the Digital Cellular Systems (‘DCS’) andthe ‘third generation’ systems, such as Wide-band Code Division MultipleAccess (‘W-CDMA’), also enable conversational communications but thesignals between two cellular telephone pass through a base station andthese systems are not adapted to wireless Local Area Networks (‘LAN’s)nor PANs. The conversational data packets are not transmitted inalternate directions within sets of pairs of time slots for GSM, DCS,WCDMA FDD the signal directions use 2 different frequencies, one foruplink & one for downlink, for WCDM TDD, uplink & downlink signals usethe same frequency but time slots are not managed in pairs of time slotsof the same length.

In fact there is demand for associating cellular telephones withwireless PAN or LAN links to associated devices, such as head-sets orprocessing devices so that communication occurs over the cellulartelephone system with remote cellular telephones and is relayed to theassociated head-sets or processing devices over the wireless PAN or LANlink.

Current consumption is a stringent problem in any portable application.Implementing Bluetooth or a similar communication system requirescurrent consumption and decreases the battery life time, which isespecially critical in cellular telephone applications. A secondconsequence is that the power management unit must be designed so thatit has a sufficient maximum current capability (up to 50 mA to 100 mAadditional peak current due to Bluetooth, for example) this increasesthe power management die size.

Another problem that can arise is that, the greater the powertransmitted over the wireless PAN or LAN link, the more risk there is ofinterference with other wireless PAN or LAN (like 802.11b LAN) or withcellular telephone transmissions and reception. Also, it makes sense tolimit the conversational data packets only in order to allocate morebandwidth to other terminals of the same PAN, thereby improving theQuality of Service.

The present invention addresses these and other problems.

Patent Specification U.S. Pat. No. 6,269,331 describes communicationover a GSM link in which ‘comfort noise’ is generated, that is to say awhite noise (the comfort noise is intended to give to the listener thefeeling that the call is still connected, while absolute silence in thereceiver gives the user the feeling that the call has been dropped); inthe system described in that patent specification, audio activity isdetected and blocks a comfort noise parameters are transmitted, insteadof transmitting the comfort noise itself. This patent specification doesnot describe a Bluetooth or similar link capable of full-duplextransmission of conversational data packets between two terminals inalternate directions within a set shorter than the phoneme time of pairsof time slots and does not minimize the current consumption of thewireless terminals.

Patent specification EP 1 261 176 and WO 01 08426 and ETSI publicationnumber XP-002098616 “Discontinuous Transmission (DTX) for Enhanced FullRate (EFR) speech traffic channels” describe various ways of using voiceactivity detection to enhance user comfort or to reduce occupation or tomake fuller use of the occupation of transmission channels. However, thetechnologies described do not address all the above problems of aconversational communication, especially not in the context of acommunication link like Bluetooth.

SUMMARY OF THE INVENTION

The present invention provides a method of, and a terminal for,communicating conversational data signals as described in theaccompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a communication system in accordancewith one embodiment of the invention based on the Bluetooth standard,given by way of example,

FIG. 2 is a diagram of HV2 signals transmitted and received in a knownPAN/LAN communication system using the Bluetooth standard,

FIG. 3 is a diagram of signals transmitted and received in a knowcellular telephone communication system using the GSM standard,

FIG. 4 is a diagram of signals transmitted and received in a PAN/LANcommunication system in accordance with the embodiment of the inventionillustrated in FIG. 1 based on the Bluetooth standard,

FIG. 5 is a block schematic diagram of a Bluetooth terminal inaccordance with an embodiment of the invention for use in the system ofFIG. 1, given by way of example, and

FIG. 6 is a schematic diagram of a communication system in accordancewith another embodiment of the invention including a cellular telephonelink and a link based on the Bluetooth standard, given by way ofexample,

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The general architecture of a system incorporating one embodiment of thepresent invention is shown in FIG. 1 and includes Bluetooth userterminals A and B comprising respective head-sets which includemicrophones 1 and 2 and earphones such as 3 and 4 respectively. Theterminals A and B are in radio communication with Bluetooth accesspoints 5 and 6 respectively, the communication between the Bluetoothaccess points 5 and 6 being completed by a network 7, which may includewired and/or wireless links. Each of the terminals are transceivers,that is to say that each of them includes both radio receiver andtransmitter capability for the Bluetooth link. The protocol forcommunication according to the present Bluetooth standards isillustrated in FIG. 2 by way of example. Data signals are transmittedbetween the terminals A and B over Bluetooth radio links withfull-duplex transmissions. The data packets are transmitted in alternatedirections within pairs of time slots such as T1 to T16, a basic phonemeperiod of the communication comprising a set of 16 pairs of time slotseach of length 0.625 mS. The phoneme time is an audio time interval thatis just too short to be distinguished by a listening user.

In conversational communication such as voice conversation, when A istalking to B then, after at most a short period of full duplex, the userB usually stops speaking and listens to A. The device A must transmitaudio data, in particular voice data, and the device B must receivethese audio data but there is in fact no need during unidirectionaltransmissions for A to enable its Bluetooth data receiver capability norfor B to enable its Bluetooth data transmitter capability in the B→Atime slots.

For asymmetric A to B data flow (unidirectional data flow streams from Ato B), it is usually required that the devise B acknowledges thereceived packets from A thanks to Null packets; by this means, the ABluetooth device knows if it can transmit a new packet or if it has torepeat the previous one. In a speech Bluetooth link, however, voicepackets are not acknowledged because they are not repeated. Accordingly,it is possible to switch off the B receiver and the A transmitter in theB→A time slots (and vice versa). The following scheme explains this whenthe headset owner is talking (the headset being the A device) VoiceActivity Voice Activity Detection Detection A B Actions for the next 16time slots Voice Voice A: Tx + Rx Full duplex B: Tx + Rx No Voice VoiceA: Rx Half duplex B to A B: Tx + local comfort noise if headset Voice NoVoice A: Tx + local Half duplex A to B comfort noise if headset B: Rx

For this purpose, both Bluetooth devices A and B integrate a VoiceActivity Detector that detects if the local Bluetooth device user istalking. The voice activity detection is synchronized between the twoBluetooth devices A and B by sending from each of the terminals A and Bto the other one, during each of the phoneme periods, a conversationalactivity signal indicative of the detected local conversational activityat the corresponding local terminal. When voice activity is detected atonly one of the terminals, the Bluetooth link (which has a full-duplexaudio link capability) is implemented as a half-duplex voice Bluetoothlink, starting from the next phoneme period and until voice activity isdetected again at the other, silent terminal. The Bluetooth voice flowis controlled by a control mechanism responsive to the conversationalactivity signal that synchronizes the transmission/reception control ofthe two terminals A and B by transmitting and receiving periodically,once during each phoneme period, in the same time slot pair, the statusof the transmitting terminal. In this way, when there is no voiceactivity at one of the terminals A or B, no power is transmitted for thetime slot pairs within the next phoneme time, reducing the risk ofcollisions and interference, also the current consumption is reduced bythe non-functioning transmit elements at one terminal and receiveelements at the other.

A Voice Activity Detector is included in a GSM telephone and FIG. 3shows how a Silence Insertion Descriptor (‘SID’) packet 8 is inserted ina GSM frame. The GSM frame comprises a transmit channel Tx and a receivechannel Rx, the SID packet being included in the receiver channel Rx toavoid having to transmit a white noise comfort signal and hence toreduce coder/decoder (‘CODEC’) calculations. Even when there is no voiceactivity at one of the telephones, the payload is not reduced since thetransmit and receive packets are of fixed length, no reduction in thebandwidth used is obtained, nor reduction in collisions or interference,no reduction in current consumption of the radio transceivers isobtained either, since each telephone maintains transmit and receivecapability during the whole frame.

FIG. 4 shows the method of this embodiment of the present invention asapplied to Bluetooth communication when A is talking and B is listeningafter the voice activity signal has been received so as to synchronizethe control of the terminals A and B, the Bluetooth audio stream goesfrom A to B. The Bluetooth channel from B to A is not needed and is notused. The receiver elements of the A device are shut-down. The A devicelocally generated a comfort noise from a locally generated white noisesignal so that the user of A does not feel that the communication linkis lost when the terminal A does not receive a voice signal from B. TheB microphone and associated transmit elements are shut-down.

The audio link is controlled by means of a data line (RFCOMM logicallink, for example) so that each unit knows what part of its owntransceiver must be turned on. The voice activity detector is enabledever 32*Ts=20 ms (Ts=625 μs, being the Bluetooth time slot). Thissampling rate of the audio channel activity is the phoneme period. Inthis embodiment of the present invention, the voice activity signal istransmitted only by the terminal whose transmitter is active, asdescribed above and the absence of a voice activity signal at thereceiving unit is interpreted as a negative (‘No Voice’) activitysignal, however, in another embodiment of the present invention as shownin FIG. 4, the inactive transmitter is re-activated during one slot inevery phoneme period (20 mS) to transmit a negative (‘No Voice’) voiceactivity signal. During half-duplex transmission from A to B, as shownin FIG. 4, the transmitter of the terminal A is activated to transmitand the receiver of the terminal B is activated to receive in the firstslot of each pair T1 to T15. The receiver of the terminal A and thetransmitter of the terminal B are deactivated, so that no signals areexchanged during the second slots of each pair T1 to T15. During thelast pair of time slots T16, the voice activity signal or signals aretransmitted and used to control the activation/deactivation of thetransmitters and receivers during the following phoneme period.

There are three kinds of Bluetooth wireless audio links (as described inthe Bluetooth 1.1 standard):

-   -   HV1 link (high power, high quality)    -   HV2 link (mid power, mid quality)    -   HV3 link (low power, low quality)

When the embodiment of the present invention shown in FIG. 4 is appliedto an HV2 or HV3 Bluetooth link, the HV2 or HV3 audio link is controlledby an Asynchronous-Connection-less Link (ACL). VAD status aretransmitted using this ACL. Ideally they are transmitted with DM1 (asdescribed in the Bluetooth 1.1 standard) packets, which are reliablepackets thanks to the inclusion of correction bits. The payload may beas short as 60 bits (5 bytes payload header, VAD command, VADresult-CRC16 encoded with a 2/3 coding rate). When the talking Bluetoothdevice reads the VAD status of the listener Bluetooth device, it knowsif it had to switch to receive mode, switch to full duplex mode (arelatively unusual usage case), or hold in transmit mode. As aconsequence, this ACL link is used to control the audio flow.

When the embodiment of the present invention shown in FIG. 4 is appliedto an HV1 Bluetooth link, once again the HV1 audio link is controlledwith an ACL link that is managed by the upper stack layers. Howeverthere are no Bluetooth time slots free to transmit this audio flowcontrol information because an HV1 link requires the whole Bluetoothchannel Bluetooth bandwidth, so the audio flow control information istransmitted using a DV packet (as defined in Bluetooth 1.1specification) which merges audio and control data in the same packet(DV packet). The audio field is not protected with parity bits, as aconsequence, there are potential error in this audio packet. However,upwards digital processing (interpolation) can minimize the audioeffects of those errors.

FIG. 5 shows a Bluetooth terminal for use in the system of FIG. 1,comprising a receiver 11 connected to receive Bluetooth signals from anantenna and supply audio signals to headphones 12 and a transmitter 13connected to receive transmit audio signals from a microphone 14 andtransmitting Bluetooth signals through the antenna. A voice activitydetector 15 detects the audio signals from the microphone 14 in eachphoneme period and provides a detector signal to the transmitter 13,which transmits a corresponding local voice activity signal over a ACLBluetooth link to the remote Bluetooth terminal with which the localterminal is in communication. The receiver 11 also detects any remotevoice activity signals receive over the ACL link from the remoteterminal. A controller 16 responds to both the local voice activitysignals and the remote voice activity signals and controls a powersupply 17 to the receiver 11 and a power supply 18 to the transmitter13.

The controller 16 responds to conversational activity occurring at afirst one of the terminals (A, B) and not occurring at the second one ofthe terminals (B, A) by controlling the receiver 11 and transmitter 13to communicate by half-duplex transmission of the audio packet. Duringthe half-duplex transmission the controller 16 at least partiallydeactivates either the reception means in the absence of remoteconversational activity or said transmission means in the absence oflocal conversational activity so as to reduce power consumption. Thedeactivation may consist of cutting off the power supply to at leastpart of the receiver or the transmitter. The receiver is preferablyreactivated at least once per phoneme period to check for reception ofany remote voice activity signals over the ACL link from the remoteterminal.

The present invention is applicable to communication between two simpleBluetooth terminals A and B through Bluetooth access points 5 and 6 anda network 7, as in the embodiment of FIG. 1. Concerning wired networks,there are a lot of different flow control standards depending on thephysical link and logical communication link types. For example,L1/N5/R2, sea & satellite standards, TCP/IP offer audio flow controlfacilities to reduce the needed bandwidth. As they mostly implement VAD(because of echo cancellation necessary implementation) facilities, theyare compatible to work with the idea which is detailed here.

However, the invention is also applicable in a situation as shown inFIG. 5 where at least the terminal B communicates with a third terminalC over a further communication link, the terminal B signalling aconversational activity signal indicative of conversational includecellular telephone modules and the terminal B also includes a Bluetoothmodule of the kind described with reference to FIG. 1.

The mobile phone already includes a VAD module. It avoids transmittingsilence frames through the cell-phone network during pauses or whensomeone else is talking. In the preferred embodiment of the invention,the silence detection is based on cumulated sound energy detection. Thesilence control is managed between the remote and local cell-phonesusing an information update through a data channel. In anotherembodiment of the invention, silence data packets are compressed andsignalled using a “SID” packet 8, containing the silence durationinformation, as described with reference to FIG. 3.

In these embodiments of the invention, the mobile phone VAD and theBluetooth wireless headset VAD are synchronized (using a VAD stateinformation transmitted through an ACL data link) in order to determinewhich device is producing silence and which on is producing voice. TheLocal device B acts as an audio gateway between the Remote device andthe Local Bluetooth device.

In full-duplex mode, each of the devices is emitting and receivingaudio. There is no network optimization. This mode is unusual (becauseit assumes that each user is speaking without listening to the otherone), except that it can happen in half-duplex modes transition (whentransmission switches from C torwards B to B towards C).

When C is talking to A, then after a short period of full duplex, theuser A stops speaking and listens. The remote terminal C transmits audiodata over the cellular telephone link and the local terminal B receivesthis audio data. The local terminal B transmits audio data over theBluetooth link and the Bluetooth terminal A receives this audio data.There is then no need for B to enable its Bluetooth receiver in the A toB time slots and it is deactivated in response to the absence ofdetection of remote conversational activity at the terminal A from theconversational activity signals received at B over the Bluetooth link.Equally, there is no need for A to enable its transmitter in the A to Btime slot and it is deactivated in response to the absence of detectionof local conversational activity at the terminal A.

Conversely, when A is talking to C, then after a short period of fullduplex, the user C stops speaking and listens. There is no need for A toenable its Bluetooth receiver in the B to A time slot and it isdeactivated in response to the absence of detection of remoteconversational activity at the terminal C from the conversationalactivity signals received at A over the Bluetooth link. Equally, thereis no need for B to enable its transmitter in the B to A time slot andit is deactivated in response to the absence of detection of remoteconversational activity at the terminal C from the conversationalactivity signals received at B over the cellular telephone link.

It will be appreciated that when the communication occurs betweenterminals all using the same communication standards (the Bluetoothstandards, for example), the same activity procedure is used insynchronization between all the terminals. However, in a case such asthat described with reference to FIG. 5, where communication overdifferent links occurs using different communication standards (cellulartelephone standards for the link between B a C and Bluetooth standardsfor the link between A and B, for example), the different activityprocedures are used and the voice activity signal received in onestandard is used to generate the voice activity signal to be transmittedin the other standard to obtain the synchronization between all theterminals.

1. A method of forming a package device, comprising; providing a packagesubstrate having a first side and a second side and having first pads onthe first side and second pads on the second side; placing a firstintegrated circuit on the first side and a second integrated circuit ona second side; electrically connecting the first integrated circuit tothe first pads and the second integrated circuit to the second pads; andtesting the first integrated circuit and the second integrated circuitby applying test probes to the first pads and the second pads.
 2. Amethod for forming a package device, comprising: providing a packagesubstrate having a first surface along a first plane and second surfacealong a second plane, wherein the package substrate has a cavity betweenthe first plane and the second plane; placing a first integrated circuitin the cavity; placing a second integrated circuit adjacent to the firstintegrated circuit outside the cavity; and depositing encapsulatingmaterial over the first integrated circuit and the second integratedcircuit.
 3. The method of claim 2, wherein the step of depositingcomprises: depositing a first portion of the encapsulating material overthe first integrated circuit prior to the step of placing the secondintegrated circuit; and depositing a second portion of the encapsulatingmaterial over the second integrated circuit.
 4. The method of claim 2,wherein the package substrate further comprises a supporting memberalong the second plane of the substrate.
 5. The method of claim 4,further comprising removing the supporting member prior to step ofplacing the second integrated circuit.
 6. A package device, comprising:a package substrate having a first surface defining a first plane and asecond surface defining a second plane, the package substrate having acavity between the first plane and the second plane; a first integratedcircuit in the cavity; and a second integrated circuit, coupled to thepackage substrate, outside the cavity.
 7. A package device, comprising:a package substrate having a first side and a second side; first pads onthe first side; second pads on the second side; a first integratedcircuit mounted to the package substrate; wherein the first pads and thesecond pads are further characterized as being useful for receiving testprobes for testing.
 8. The package device of claim 7, further comprisinga second integrated circuit mounted to the package substrate.
 9. Thepackage device of claim 8, wherein: the first integrated circuit iselectrically connected to the first pads; and the second integratedcircuit is electrically connected to the second pads.
 10. The packagedevice of claim 9, wherein the substrate is further characterized ashaving a cavity and the first integrated circuit is furthercharacterized as being in the cavity.